Type-writer escapement mechanism.



M. H. Lockwoon. TYPE WRITER ESOAPEMENT MEGHANiSM.

APPLICATION FILED MAY 20, 1911.

Patented Mar. 5, 1912.

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M. H. LOCKWOOD.

TYPE WRITER BSCAPEMBNT MECHANISM.

APPLICATION FILED MAY 20, 1911.

Patented M21115, 1912.

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ggflAazzuw'wr ATTORNEYS UNITED STATES PATENT oEEioE.

MARQUIS H. LOCKWOOD, OF NEW YORK, N. Y., ASSIGNOIR. TO UNDERWOOD TYPEWRITE'R. COMPANY, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE.

TYPE-WRITER ESCAPEIVIENT MECHANISM.

Patented Mar. 5, 1912.

Serial No. 628,537.

To all whom it may concern:

Be it known that I, MARQUIS H. Loon- WOOD, residing in the borough of Manhattan, city, county, and State of New York, have invented certain new and useful Improvements in TypeNVriter Escapement Mechanism, of which the following is a specification.

My invention relates to an escapement adapted for operation, without adjustment, either at high speed or at ordinary speed.

Usually an escapement for ordinary speed of operation is provided with very little drop while for high speed operation a considerable amount of drop is desirable; hence machines are fitted with one or the other to meet the wishes of the operator.

The object of my invention is to provide in a single escapement the advantages of both the above by arranging the device to automatically provide the drop required for either ordinary or high speed operation.

My invention may be carried out in a number of ways including the forms hereinafter described which consist primarily of a bifurcated or double dogged loose pawl, one dog of which is adapted to normally hold the rack from advancing while the other is adapted to prevent the escape of more than one tooth of the rack at a time, together with means which is brought into action only when a type key is held down, or when the return of the key is delayed in slow operation, to temporarily detain the rack from advancing until the key is released to permit the dog-rocker to start on its return stroke.

In the accompanying drawings, Figure 1 represents a section illustrating the key action of the well-known Underwood machine with one form of my escapement invention. Fig.2 is a perspective View of the clogrocker, and one form of the bifurcated pawl. Figs. 3, 4E and 5 represent different steps in the operation of this form of escapement. Fig. 6 represents a rear elevation of the dog-rocker and parts representing another form of the invention. Fig. 7 is a plan view of the parts shown in Fig? 6; Figs. 8, 9, 10 and 11 represent steps in the operation of this form of the invention.

As shown in Fig. 1, 1 represents the typewriter platen, while 2 is a type bar pivoted in the segment 3 at 1, and adapted to strike gaged by and thereby hold the escapement wheel or rack 12 from advancing when the machine is the printing line on the platen in the usual manner. An intermediate bell crank lever 5 pivoted in the frame of the machine 6 connects the heel of the type bar with key lever 7, the key lever being pivoted in the frame of the machine at S. In this machine, when a key is operated, the type bar 2 is adapted to strike the universal bar 9 and rock the universal frame 10, and thereby actuate the dog-rocker 11. The platen 1 is mounted in a carriage which is spring-actuated in the well-known manner and is connected with the escapement wheel 12 in such a way that when the dog-rocker is actuated, the carriage is given a step by step letter space feed in the usual manner. These parts and the general operation of the typewriter being well known, I shall confine my description to my improved escapement.

On the dog-rocker 11, in the form of injvention shown in Figs. 1 to 5, I mount a loose pawl 13, pivotally mounted upon the screw 14 to vibrate in the plane of escapement wheel 12, a tooth 12 of which is represented in dotted lines in Fig. 2. The loose pawl 13 is provided with two integral dogs 15 and 16, one of which, 15, is normally in V engagement with a tooth of the escapement wheel whereby the loose pawl is held against the action of the spring 17, and in contact with the shoulder or lug 18 on the arm of the dog-rocker carrying the screw 19 which is adapted to receive the actuating blow from the universal bar frame 10. The dog- 'rocker is pivoted in the usual manner at 20 and is thus adapted for movement transversely to the plane of the escapement wheel Mounted on the clog-rocker is a fixed dog 21 which is secured to the dog-rocker in such a position that it will be brought into engagement with the escapement wheel only when the dog-rocker has been moved backward practically to its full extent, as will be seen in Fig. 1 of the drawings. Each tooth 12 of the escapement wheel is provided with two working faces, one of which, 22, is at .right angles to the plane of the escapement wheel or rack 12, while the other, 23, is at an angle to the first working face and to the plane of the escapement wheel or rack. The first working face 22 is adapted to be enthe dog 15 on the loose pawl 13 at rest or in normal position. From the drawings it will also be seen that the fixed dog 21 is provided with a single working face 24: which corresponds in angle to the working face 22 on an escapement wheel tooth 12 and is adapted to be engaged by such face of a tooth when the dog-rocker has been moved backward so as to bring the dogs into the position represented in Fig. 4E. The amount of landing or engagement between the fixed dog 21 and a tooth of the escapement wheel is arranged to be about twenty-five thousandths of an inch. It will be understood that in escapements as ordinarily arranged, this amount of landing, namely, twenty-five thousandths of an inch, would not be sufficient to prevent skipping, or the escape of more than one tooth of the escapement wheel when the machine is operated. Nevertheless, it will be seen that if the machine can be safely operated with this slight amount of landing or engagement between the fixed dog and the escapement wheel and retain the wide space, such as I provide, between the normally holding loose dog and the fixed dog, the escapement wheel, or rack, will be released much sooner during the return motion of the type bar and key to normal position, and thereby permit an in creased speed of operation of the machine. In order to take advantage of this fact and obtain this increased speed of operation, and at the same time prevent skipping, I have provided a loose pawl 13 with two dogs 15 and 16, one of which, 15, corresponds to the ordinary loose dog and is normally held in engagement with the rack. The other dog 16, is spaced away from the normally hold ing dog in two directions so that there is room between them for the passage of a tooth of the escapement wheel or rack. The working face of the second dog 16, it will be seen, stands considerably back of the working face of the dog 15, so as to permit practically a free movement of the escapement wheel or rack as the dog-rocker returns to normal position, while at the same time this second dog 16 will prevent the escape of more than one tooth 12 of the escapement wheel, when the latter is freed from engagement with the fixed dog 21. As will be seen from the dia grammatic views in Figs. 35, the loose pawl 13 will be drawn forward by the spring 17 as soon as the dog-rocker has been moved so as to bring the dog 21 into engagement with the tooth 12 of the escapement wheel. This position of the parts is represented in Fig. 4, which is the position occupied by the parts when a typewriter key is fully depressed. It will be seen that in this position the loose pawl, drawn forward by the spring 17, has moved the dog 16 toward the tooth 12" of the escapement wheel and into engagement therewith, so that as soon as the type key is released, the fixed dog 21 will be disengaged from the escapement wheel tooth and the tooth, being in engagement with the dog 16, will force both dogs and the entire pawl 13 back to the position represented in Fig. 5. Further transverse motion of the dog-rocker will permit the tooth 12 of the, escapement wheel to pass between the two dogs l5-and 16 on the pawl and the succeeding tooth will engage the dog 15 and hold the escapement wheel or rack with the parts in the normal position as represented in Fig. 3 of the drawings.

From the drawings it will be noticed that the dog 21 is undercut at 21 in order to al low the dog 16 to advance and engage the tooth of the escapement wheel when the tooth is also in engagement with the fixed dog 21. This is merely to permit making the dog 16 wider and stronger.

Another form of the invention is repre sented in Figs. 6 to 11. In this form the loose pawl 13 of the previously described form of construction is replaced by a similar pawl 25, which is provided with two relatively fixed dogs 26 and 27, spaced apart diagonally so as to leave them for a tooth 12 of the escapement wheel 12. The dog 26 is normally in engagement with a tooth 12 of the rack or escapement wheel as illustrated in Fig. 8 of the drawings. In this form, instead of the fixed dog 21, adapted to temporarily hold the rack from advancing when the key is fully depressed, I have provided another form of dog or pawl 28 which is pivotally mounted by the screw 29 on a bracket 30, se cured to the dogrocker frame 31. The bracket 30 is also provided with a lug 32 through which passes a screw 33, arranged to serve as a stop for the pawl 28 by contacting with an arm 34 extending therefrom and integral therewith. The pawl or dog 28 is provided at 35 with a hook or working face adapted to stand normally about in line with the working face of dog 26, but it will be understood that the position of the hook should be determined by the movement of the pawl 25 to bring the dog 27 into engagement with the tooth 12 of the escapement wheel. The loose pawl 25 is adapted to be movedunder tension of a light spring 17, in the plane of the escape ment wheel, so as to bring the second dog 27 into engagement with the tooth of the escapement wheel which has been disengaged from the normally holding dog 26 by a transverse movement of the dog-rocker. This movement of the pawl 25 is toward the right, as seen in Figs. 6 to 11 in the drawmgs, and its motion in this direction is limited by the head of the screw 36, which is eccentric, so that by turning the screw the limit of mot-ion of the pawl 25 may be varied. A similar screw is shown in Fig. 2 of the drawings in connection with the a passage between first form described. The hook or working face 35 of the pawl 28 is so located with relation to the pawl 25 that when the pawl 25 is moved transversely by actuating the dog-rocker to the position shown in Fig. 9 of the drawings, the point of the hook will contact or be in position to contact with the dog 26; and the instant pawl 25 is released by the disengagement of the dog 26 from the escapement wheel 12, the pawl will be drawn forward under the tension of the spring 17 to the position illustrated in Fig. 10 of the drawings, where the dog 27 is shown in engagement with a tooth 12 of the escapement wheel. This will occur because the pawl 25 being of such light weight; as compared with the carriage, will have time under the impulse of its spring 17, to snap forward and meet the released tooth of the escapement wheel before the inertia of the heavy carriage has been overcome and the escapement wheel has had time to move an appreciable amount. In this position of the pawl 25, the hook 35 of the pawl 28 will snap into holding position back of the dog 26, and thus prevent theescapement wheel from moving until the dogrocker has started on its return movement and drawn the dog 26 out of engagement with the hook 35. A light spring 37 is adapted to keep the pawl 28 under tension so as to restore it to and hold it in position for the hook 35 to engage the rear edge of the dog 26 in the manner just described. The screw 33 is adjusted so that the hook 35 of the pawl 28 extends over the rear edge of the dog 26, about twenty-five thousandths of an inch, or a sufficient amount to hold the pawl 25 temporarily at the extreme of its transverse movement. It will thus be seen that when a key is fully depressed and the parts are in the relative position shown in Fig. 10 of the drawings the rack tooth 12 will be released from engagement with the dog 26, but the rack will be prevented from advancing by the engagement of the hook 35 with the dog 26, but this holding engagement between the hook 35 and the dog 26 is so slight that as soon as, or practically as soon as the key is released the pawl 25 is released. A small amount of movement of the dog-rocker, (twenty-five thousandths at the dogs), will be suflicient to release the dog 26 from engagement with the hook 35, and thus permit the rack to move forward so as to begin the feed of the carriage much sooner than would be the case in the usual style of escapement. Fig. 11 of the drawings represents the parts when the dog-rocker is partially restored to normal position and the spring 17 has been permitted to draw the pawl 25 farther toward the right.- This position would, of course, be assumed only in rapid operation where the dog-rocker would return to normal position before the escapement wheel had advanced the full letter space distance.

The principle of operation of the invention is as follows. At moderate to high speed operation the rack is released from the normally holding dog of the loose pawl and is practically free to make the full letter space movement without interruption, while for ordinary speed or with considerable dwell on the keys the rack will be detained temporarily and the carriage will be held while the type is at the printing point, or until the return movement of the key and dog-rocker begins. In one of the forms described the rack is held by the fixed dog contacting with a corner face of a rack tooth, the second dog on the loose pawl protecting the wide space between the normally holding dog and the fixed dog and insuring the escapement of but one tooth of the rack. In the second form the rack is held by temporarily holding the loose pawl by means of the relatively fixed hook pawl in an advanced position, with the second dog on the loose pawl in engagement with the tooth of the rack which has just been disengaged from the normally holding dog on said pawl.

Various forms and modified structures may be devised to accomplish the above objects without departing from the scope of my invention.

I claim:

1. In an escapement for typewriters the combination of a rack, a bifurcated loose pawl cooperating therewith said pawl being actuated to move in opposition to the feed movement of the rack and means for actu- 1 ating said pawl to produce step by step feed of said rack.

2. In an escapement for typewriters, the combination of a rack, a bifurcated loose pawl adapted for feeding the rack tooth by ltooth by two movements of the pawl, one

transversely to and the other in the plane of said rack and means for actuating said pawl to permit feed of said rack.

3. In a typewriter escapement the con1- bination of a rack, a pawl movable relatively to said rack in two directions for feeding said rack step by step, a plurality of dogs on said pawl adapted to successively engage said rack as the pawl is moved, and means for actuating said pawl to permit feed of said rack.

l. In a typewriter escapement the combination of a rack, a pawl movable parallel with and actuated in opposition to the feed movement of the rack and also movable transversely to said rack to permit feed of the same step by step, a plurality of dogs on said pawl adapted to successively engage said rack and means for moving said pawl.

5. In a typewriter escapement the combination of a rack, a support movable relatively to said rack, a loose pawl carried by said support and actuated to move in opposition to the feed movement of the rack, a plurality of dogs on said pawl, arranged to successively engage said rack as said support is moved the engagement-being hastened by said movement of the pawl, and means for actuating said support.

6. In a typewriter escapement the combination of a rack, a support movable relatively to said rack, a loose pawl carried by said support, a plurality of dogs on said pawl arranged to successively engage said rack as said support is moved, independent means, brought into action at the end of the motion of said support in one direction for temporarily holding said rack from advanc ing until the beginning of the return motion of said support, and means for actuating said support.

7. In an escapement for typewriters 'a rack, a key actuated dog-rocker, a loose pawl pivotally mounted on the dog-rocker, two dogs on said pawl, one normally in engagement with the rack and means brought into action when a key is fully depressed, for temporarily holding the rack from advancing while the other of said dogs is in engage ment therewith.

8. In an escapement for typewriters a rack, a loose pawl movable both transversely to and in the planeof the rack, two dogs on said pawl, the one adapted toengage and normally hold the rack, and the other adapted for engagement with the rack when the first is disengaged therefrom and means brought into action when the normally holding dog is disengaged, for temporarily holding the rack from advancing while the other of said dogs is in engagement therewith.

9. In an escapement for typewriters, a rack, a loose pawl movable both transversely to and in the plane of the rack, two dogs on said pawl, the first adapted to engage and normally hold the rack, and the second adapted for engagement with the rack when the first is disengaged therefrom, means for moving the pawl transversely to disengage the first dog, means for moving said pawl in the plane of the rack to engage the second dog with the rack and independent means for temporarily holding the rack from advancing while the second dog is in engagement therewith.

10. In an escapement for typewriters, a rack, a loose pawl movable both transversely to and in the plane of the rack, two dogs on said pawl, one adapted to engage and normally hold the rack and the other adapted for engagement with the rack when the first dog is disengaged therefrom, key-actuated means for moving said pawl transversely to said rack to disengage the nor mally holding dog, means for moving said pawl in the plane of the rack to engage the second dog with the rack and an independent dog, fixed relative to the feed movement of the rack but movable transversely thereto and adapted to hold the rack from advancing while the second dog on said pawl is in engagement therewith until the begin ning of the return transverse movement of said pawl.

11. In an escapement for typewriters, a rack, a key-actuated dog-rocker, a bifurcated loose dog, pivoted on the dogrocker each bifurcated portion being provided with a single working face, the two working faces being spaced apart in the direction of feed of the rack, one working face being adapted to normally engage the rack, and means for temporarily holding the rack from advancing while the second working face is in engagement therewith.

12. In an escapement for typewriting machines, a rack, a key-actuated dog-rocker movable transversely to the rack, a pawl pivoted to the dog-rocker and adapted to vibrate in the plane of the rack,a dog on said pawl adapted to engage and normally hold said rack, a second dog on said pawl adapted to engage the rack when the normally holding dog is disengaged therefrom by a movement of said dog-rocker and means for holding the rack from advancing, while the said second dog is in engagement therewith, until the dog-rocker begins its return move ment.

13. In an escapement for typewriters, a rack, a dog-rocker mounted to rock transversely to the rack, a key adapted to actuate the dog-rocker in one direction, a pawl pivoted on the dog-rocker to vibrate in the plane of the rack, two dogs on said pawl, the first normally in engagement with the rack and the second adapted to engage the rack when the first is disengaged, and means for holding the rack from advancing, while said second dog is in engagement therewith, until. the actuating key is released.

14. In an escapement for typewriters, a rack, a key-actuated dog-rocker, a loose pawl pivotally mounted on the dog-rocker, two dogs on said pawl one normally in engagement with the rack and an independent fixed dog adapted to hold the rack from advancing when the normally engaged dog on said pawl is disengaged and the other dog on said pawl is in engagement with the rack.

15. In an escapement for typewriters, a rack, a dog-rocker, a loose pawl pivoted on the dog-rocker, two dogs on said pawl, a fixed dog on said dog-rocker adapted to engage the rack while one of the dogs on said loose pawl is brought into engagement with said rack, and means for moving said pawl both transversely to and in the plane of said rack.

16. In an escapement for typewriters a rack, a key-actuated dog-rocker, a loose pawl pivotally mounted on the dog-rocker, two dogs on said pawl, one normally in engagement with the rack and a fixed dog on the dog rocker adapted to be brought into engagement with the rack when the key is fully depressed and hold said rack from advancing while the normally disengaged dog on said loose pawl is in engagement therewith.

17. In an escapement for typewriters, a rack, a loose pawl movable both transversely to and in the plane of the rack, two dogs on said pawl, one adapted to engage and normally hold the rack and the other adapted for engagement with the rack when the first is disengaged therefrom, and a fixed dog movable transversely to said rack and adapted to temporarily hold the rack from advancing while the normally disengaged dog on said pawl is in engagement with said rack.

18. In an escapement for typewriters, a rack, a dog-rocker, a loose pawl pivoted on said dog-rocker and adapted to move transversely to and in the plane of said rack, two dogs on said pawl, one of which is normally in engagement with the rack and the other adapted to engage said rack when the first is disengaged, means for moving said pawl in the plane of the rack to bring the second dog thereon into engagement with said rack when the first is disengaged and means for temporarily holding the pawl while said second dog is in engagement wit-h the rack.

In testimony whereof, I have hereunto set my hand in the presence of two subscribing witnesses.

MARQUIS H. LOCKWOOD.

Witnesses:

JOHN H. HILLIARD, J OHN A. KEHLENBEOK.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. G. 

